Nasal air flow detection method for speech evaluation

ABSTRACT

Apparatus for detecting the presence of nasal air escape during speech. A thermistor is placed in the path of nasal air flow, and air flow over the thermister lowers the temperature of the thermistor creating a voltage change in a bridge circuit. The voltage change is amplified and processed by an analog-to-digital converter, and relative values of the voltage change are displayed by a digital readout. The detected nasal air flow correlates closely with the degree of nasality of the human voice, which in turn is a correlation of nasal emission.

'United States Patent [191 Habal Sept. 23, 1975 NASAL AIR FLOW DETECTIONMETHOD FOR SPEECH EVALUATION [76] Inventor: Mutaz B. Habal, 3848Knollton Rd.,

Indianapolis, Ind. 46208 [22] Filed: Feb. 15, 1974 [21] Appl. No.:442,926

[52] U.S. Cl. 128/2 R; 128/2.08; 179/1 SC [51] Int. Cl. A6113 10/00 [58]Field of Search 128/2 H, 2 R, 2 C, 2.08,

128/D1G. 29; 73/204; 179/1 SC [56] References Cited UNITED STATESPATENTS 2,831,181 4/1958 Warner 128/D1G. 29

3,316,902 5/1967 Winchel et al 128/2.08 3,383,466 5/1968 Hillix et al.179/1 SC 3,621,835 11/1971 Suzuki et al. 128/2.08 3,645,133 2/1972Simeth et al... 128/2.08 3,759,249 9/1973 Fletcher 128/2.08

OTHER PUBLICATIONS Hilberman et al., On Line Assessment pulmonarypathophys." J. A. A. of Medical lnst., Vol. 6, No. 1, Jan-Feb. 1972, pp.65-69. Nasa Tech. Brief, 68-10438, December 1968, Nosepiece Resp.Monitor.

Hershberg, Postop. Pneumographic Monitoring Unit, Am. J. of Med. Elec..,July-September 1963, pp. 207-211.

Gundersen, Reg. of Breathing Rate with Twin Therm.", Proc. of 1st NordicMeeting Med. & Bio. Eng, pp. 158-160, Jan. 1970.

Graystone, Self-cent. Resp. Monitor Animal Re search, IEEE Trans. onBio-Med. Eng. Sept. 71, pp. 382-383.

Primary Examiner-Richard A. Gaudet Assistant Examiner-Lee S. CohenAttorney, Agent, or Firm-Woodard, Weikart, Emhardt & Naughton [57]ABSTRACT Apparatus for detecting the presence of nasal air escape duringspeech. A thermistor is placed in the path of nasal air flow, and airflow over the thermister lowers the temperature of the thermistorcreating a voltage change in a bridge circuit. The voltage change isamplified and processed by an analog-to-digital converter, and relativevalues of the voltage change are displayed by a digital readout. Thedetected nasal air flow correlates closely with the degree of nasalityof the human voice, which in turn is a correlation of nasal emission;

3 Claims, 2 Drawing Figures Sheet 1 of 2 Sept. 23,1975

US Patent US Patent Sept. 23,1975 Sheet 2 of2 3,9 36

NASAL AIR FLOW DETECTION METHOD FOR SPEECH EVALUATION BACKGROUND OF THEINVENTION 1. Field of the Invention The invention is in the field ofspeech analysis.

2. Description of the Prior Art The presence of nasal emission inpatients after reconstruction of clefts of the secondary palate, and inother physical pr physiological conditions, denotes an incompetence inthe velopharyngeal valve mechanism. Other than in the obvious cases inwhich there is complete incompetence of the valve, there is usually aproblem in evaluating the patients condition. The incompleteincompetence of the velopharyngeal port can be hard sometimes todifferentiate from articulation problems, neuromuscular incoordination,or functional nasality; and, in such conditions, testing for nasalescape has been found to be helpful in differentiating among the variousproblems encountered and a good adjunct to speech evaluation. The degreeof nasal air emission correlates well with nasality of speech.

Several conventional and unscientific methods have been used by speechtherapists and surgeons to detect the air escape during speech, such asfogging of a mirror placed beneath the nostrils, the blowing on smallcotton threads, tissue paper or soap bubbles placed in front of thenostrils,'or pinching of the nostril to detect change in voice quality.All of these methods typically have been utilized during the recitationby a patient of a given standard phrase, test sentence, vowel, orconsonant which may be sibilant or plosive. Other recently introducedmethods, with more scientific bases, such as spirometry measurement, airflow measurement with an anethesia mask, and ultrasonic devices areamong the methods utilized by surgeons and speech therapists for theseproblems. More complex, and expensive, sophisticated methods haveutilized transducer devices and ocilloscopic imaging, most of whichmethods are not used during a given speech or are invasive by nature oftheir use.

Two prior art devices for determining nasality of human speech,utilizing sound analysis, are disclosed in U.S. Pat. No. 3,281,534 toDersch and U.S. Pat. No. 3,752,929 to Fletcher. Devices using thermistorwhich are for monitoring breathing are disclosed in U.S. Pat. No.3,316,902 to Winchel, U.S. Pat. No. 3,645,133 to Simeth et al., and U.S.Pat. No. 3,735,752 to Rodder. U.S. Pat. No. 3,383,466 to I-Iillix et al.discloses a speech analysis and recognition system. U.S. Pat. No.3,410,264 to Frederick discloses a pressure sensitive transducer for usein measuring nasal air resistance. U.S. Pat. No. 2,831,181 to Warnershows another respiration monitoring device utilizing a thermallysensitive element (i.e. a thermocouple).

SUMMARY OF THE INVENTION One embodiment of the present invention is anapparatus for detecting the presence of nasal air escape during speechcomprising a device presenting at an output an electrical characteristicdependent upon the temperature of the device, first means forpositioning the device within a path of nasal air flow and not of oralair flow, and second means coupled to the output of the device forindicating relative values of the electrical characteristic.

An object of the present invention is to provide a quick and reliable,nonrestrictive and nonobstructive electrometric detection test methodwhich is easy to use for the detection of nasal. air emission inpatients with rhinophonia.

It is a further object of the present invention to provide a nasal airflow detection method useful to differentiate dysarthrophonia,neuromuscular incoordination and physical defects from nasality due toincompetent velopharyngeal valve mechanism.

It is a still further object of the present invention to provide a nasalair flow detection method useful to a patient and his speech therapistduring therapy sessions or speech exercise to detect any nasal air leakduring speech, especially when it is variable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic diagram of anasal air flow detector according to the present invention.

FIG. 2 shows a nose mask including, in a passageway for air flow, thethermistor of the circuit of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT For the purposes of promoting anunderstanding of the principles of the invention, reference will now bemade to the embodiment illustrated in the drawings and specific languagewill be used to describe the same. It will nevertheless be understoodthat no limitation of the scope of the invention is thereby intended,such alterations and further modifications in the illustrated device,and such further applications of the principles of the invention asillustrated therein being contemplated as would normally occur to oneskilled in the art to which the invention relates.

Referring in particular to FIG. 1, there is shown a schematic diagram ofan embodiment of the present invention. Thermistor l1 and resistor 12,together with resistor 13, form a voltage divider between +V and -V,. +Vand V and +12 volts and l volts respectively and are obtained from astandard DC supply. Thermistor 11 serves as a nasal air flow sensorwhich is positioned in the path of the subjects nasal air flow and ismaintained at about 50C. with no air flow across the thermistor.Thermistor 11 is a type GB32J2, and resistors 12 and 13 are selected tomaintain sufficient 'current in thermistor 11 to keep it at the 50C.temperature, with typical values of resistors 12 and 13 being 820 ohmsand 1,500 ohms, respectively.

Potentiometer 17 is coupled. to the +V supply and is set so that point16 is maintained at 0 volts when there is no air flow across thermistor11. Amplifier 18 receives its positive input from potentiometer 17 andits negative input from the voltage at point 14 coupled through resistor19. There is also a feedback resistor pair from point 16 at the outputof amplifier 18 to the negative input of amplifier 18. Either resistor21 or 22 may be switched into the feedback circuit to determine the gainof amplifier 18. Typical values for these resistors are 540K ohms and270K. ohms. Amplifier 18 is a type uA74lc.

As stated, potentiometer 17 is adjusted so that there is a 0 output ofamplifier 18 at point 16 when there is no air flow across the thermistor11. If there is air flow across thermistor 1 1, its temperature goesdown and its resistance increases. The increase in resistance ofthermistor 11 causes the voltage at point 14, and hence at the minusinput of amplifier 18, to go down and the voltage at point 16 at theoutput of amplifier 18 to go up. The gain of the amplifier 18 is suchthat the voltage at point 16 varies between and volts.

The analog voltage signal at point 16 is converted to digital form bythe next circuit stage. A voltage divider is established between +V- andV which are +5 volts and 5 volts, respectively. The resistance values inthe divider are chosen so that the voltage at point 23 is 4 volts; atpoint 24, 3 volts; at point 26, 2 volts; and a point 27, 1 volt. Each ofthese voltages is applied to the negative input of a differentcomparator. Comparators 28, 29, 31 and 32 are also uA74lc operationalamplifiers. The input to each comparator is the voltage at point 16. Atthe outputs of the comparators, the signal from amplifier 18 has beenconverted from analog to digital form. The diodes at the outputs of thecomparators prevent negative voltage excrusions so that the input toexclusive OR gates 33, 34 and 36 is TTL compatible.

The exclusive OR gates 33, 34 and 36 decode the comparator outputs intobinary coded decimal (BCD) form with only the numbers l, 2, 4 or 8possible. The BCD number is decoded by decoder driver 37 into sevensegment display form and coupled to seven sega positive output since itsnegative input is at 2 volts and its positive input is at 3 /2 volts.Comparator 29 will have a positive output because its negative input isat 3 volts and its positive input is at 3 /2 volts. Comparator 28 willhave a 0 output because its negative input is at 4 volts and itspositive input is at 3 /2 volts.

Therefore, exclusive OR gate 36 will have two high inputs and its outputwill be low. Exclusive OR gate 34 will also have two high inputs and itsoutput will be low.

Exclusive OR gate 33 will have a high input from comparator 29 and a lowinput from comparator 28, and therefore the output of exclusive OR gate33 will be high. The direct connection from the output of comparator 28to the 8-input of decoder driver 37 will be low, as stated above. Theonly high input to decoder driver 37 will be at the 4-input and decoderdriver 37 will drive seven segment readout 38 to display a 4.

The use of exclusive OR gates 33, 34 and 36 will assure that only onedigit is decoded at a time. While the analog-to-digital (A/D) conversionillustrated results in only four digits, it can be seen that theconversion scheme may be easily expanded by the addition of dividerelements, comparators and exclusive OR gates up to, for example, tendigits rather than four. In FIG. 2, there is shown a nose mask 42mounted on a nose 41 of a subject being tested for nasal air flow andnasality. Nose mask 42 has a pair of air channels such as 44, onechannel being provided for each nostril. Thermistor 11 is mounted withinair channel 44 and a second thermistor may be mounted in the other airchannel of nose mask 42. If a second thermistor is used, it may beelectrically connected in parallel with thermistor 1 l in the circuit.As can be seen, nasal air flow will be directed through air channel 44and across thermistor l l, lowering its temperature and increasing itsresistance, resulting in functioning of the circuit of FIG. 1 asdescribed. Connecting cable 43 contains the necessary connecting leadsfor the thermistor and makes the necessary electrical connections fromthe thermistor in the nose mask to the detection portion of thecircuitry as described above.

It can be seen that there has been provided a quick and reliable,nonrestrictive and nonobstructive-electrometric detection test apparatuswhich is easy to use for the detection of nasal air emission in patientswith rhinophonia.

It can also be seen that there has been provided a nasal air flowdetector which is useful to differentiate dysarthrophonia, neuromuscularincoordination and physical defects from nasality due to incompetentvelopharyngeal valve mechanism.

It can also be seen that there has been provided a nasal air flowdetector, useful to a patient and his speech therapist during therapysessions or speech exercise, to detect any nasal air leak during speech.

While there have been described above the principles of this inventionin connection with specific apparatus, it is to be clearly understoodthat this description is made only by way of example and not as alimitation in the scope of the invention.

The invention claimed is:

1. A method in the area of speech evaluation for detecting the presenceand extent of nasal air emissions of a subject during speech comprisingthe steps of:

positioning, within a path of nasal air flow of the subject, sensormeans, including a first element sensitive to temperature, forpresenting at an output an electrical characteristic dependent upon thetemperature of the first element;

having the subject speak; and

detecting relative values of the electrical characteristic of the sensormeans which are produced by nasal air emissions of the subject duringsaid speaking for the purpose of evaluating the nasal air flow of thesubject indicated by the electrical characteristic at the output of thesensor means with regard to what is spoken by the subject.

2. The method of claim 1 which comprises the additional step, after saiddetecting step, of:

producing a visual display corresponding to said relative values of theelectrical characteristic.

3. The method of claim 2 in which the step of having the subject speakcomprises having the subject speak a plurality of preselected testphrases.

1. A method in the area of speech evaluation for detecting the presenceand extent of nasal air emissions of a subject during speech comprisingthe steps of: positioning, within a path of nasal air flow of thesubject, sensor means, including a first element sensitive totemperature, for presenting at an output an electrical characteristicdependent upon the temperature of the first element; having the subjectspeak; and detecting relative values of the electrical characteristic ofthe sensor means which are produced by nasal air emissions of thesubject during said speaking for the purpose of evaluating the nasal airflow of the subject indicated by the electrical characteristic at theoutput of the sensor means with regard to what is spoken by the subject.2. The method of claim 1 which comprises the additional step, after saiddetecting step, of: producing a visual display corresponding to saidrelative values of the electrical characteristic.
 3. The method of claim2 in which the step of having the subject speak comprises having thesubject speak a plurality of preselected test phrases.